The present invention involves a telephone answering system for use in conjunction with a PBX/CENTREX system for monitoring and answering incoming calls from a central office or another PBX/CENTREX extension directed to various telephone extensions within the PBX/CENTREX system.
In order to provide each of the telephone extensions of a PBX/CENTREX system with telephone answering services, a control system has been interconnected between the PBX/CENTREX system and each of the telephone extension lines. This control system is connected in parallel across the tip and ring lines directed to each extension line. This control system monitors each of the incoming calls received on the telephone extension lines and includes a switching matrix for connecting an operator controlled telephone answering system to the tip and ring lines of such an extension when the extension remains unanswered for a preselected number of rings.
In the operation of such a telephone answering system, a tip/ring monitor is placed across each of the extension lines in the PBX/CENTREX system for counting the number of rings on the extension line in the PBX/CENTREX system. A relay switch is then provided for each of the extension lines which enables an incoming call directed to any of the extension lines to be switched from such extension line to a line connected in parallel directed to an operator controlled telephone answering system. When the number of rings on a subscriber line has been counted and exceeds a preselected number of rings without the subscriber answering his telephone, i.e. without the phone going off-hook, the call is then transferred through the switching matrix to the telephone answering service.
This monitoring of each of the telephone lines and switching of a call on such line to a telephone answering service is normally provided through a telephone line concentrator such as the concentrator marketed by the assignee of the present patent application Amtel Communications, Inc. under the name "Little Guy." Such a telephone line concentrator is connected in parallel across each of the telephone lines in the system. Such a concentrator includes a built-in relay switching matrix for connecting the calls from each of the lines to the telephone answering service.